Next generation mobile communication systems have been standardized aiming at providing integrated services and effective interoperations between a wired communication network and a wireless communication network, beyond a simple wireless communication service provided in the conventional mobile communication systems. With the demand on a high-speed, large-volume data communication system for processing and transmitting a variety of information such as radio data as well as providing voice-oriented services, there is a need for developing a technique for transmitting large-volume data through the wireless communication network whose capacity is similar to that of the wired communication network.
Therefore, a method of properly detecting errors is essential for minimizing data loss and for improving system performance by increasing system transmission efficiency. An automatic repeat request (ARQ) procedure is a process in which, if a receiver successfully receives data, an acknowledgment (ACK) signal is feedback to a transmitter, and if the receiver unsuccessfully receives the data, a not-acknowledgment (NACK) signal is fed back to the transmitter.
Layers of a radio interface protocol between a user equipment and a base station can be classified into a first layer (L1), a second layer (L2), and a third layer (L3) based on the lower three layers of the open system interconnection (OSI) model that is well-known in a communication system.
Each layer operates independently. Even if errors occur, each layer independently performs a basic operation for self-recovery. However, when communication is achieved between the base station and the user equipment, if separate ACK/NACK signals are exchanged between lower layers which are divided from one layer, the same operation is unnecessarily repeated for the same data, thereby causing deterioration in a data throughput required to transmit high rate data.
For example, a medium access control (MAC) layer and a radio link control (RLC) layer are lower layers belonging to the same layer (i.e., second layer) in a layer structure of the radio interface protocol. However, if the MAC layers of the base station and the user equipment exchange an ACK/NACK signal for the same data (i.e., a HARQ procedure) while the RLC layers of the base station and the user equipment exchange another ACK/NACK signal (i.e., an ARQ procedure), waste of resources occurs due to repetitive resource allocation and also a delay occurs in the data transfer of the RLC layers.
Accordingly, there is a need for a method capable of reducing unnecessary resource allocation by using an improved ARQ (or HARQ) procedure between layers and capable of improving a data transfer rate.